A method and apparatus for encapsulating an integrated circuit die and leadframe assembly. A prepackaged sproutless mold compound insert 71 is placed in a rectangular receptacle 91 in a bottom mold chase 81. The receptacle is coupled to a plurality of die cavities 85 by runners 87. Leadframe strip assemblies containing leadframes, integrated circuit dies, and bond wires coupling the leadframes and dies are placed over the bottom mold chase 81 such that the integrated circuit dies are each centered over a bottom mold die cavity 85. A top mold chase 90 is placed over the bottom mold chase 81 and the mold compound package 71. The top mold chase 90 has die cavities 95 corresponding to those in the bottom mold chase 81. The mold compound insert 71 is preferably packaged in a plastic film 75 which has heat sealed edges 77. The mold compound is forced through the package 75 and heat seals 77 during the molding process by the pressure applied by a rectangular plunger 101. The sproutless mold compound insert is packaged so that the mold compound will exit the packaging only where runners intersect the receptacle. The sproutless mold compound insert requires no alignment or cutting tools within the mold station. The plunger is applied using variable speed and pressure to control the rate the mold compound fills the cavities in the top and bottom mold chases, thereby avoiding voids in the completed packages and mining wire sweep of the bond wires of the integrated circuit assemblies.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for encapsulating integrated circuit lead frame and die assemblies, comprising the steps of: providing a plurality of bottom die cavity regions within a bottom mold chase; providing a mold compound receptacle spaced apart from said bottom die cavity regions, for receiving a mold compound insert; providing a plurality of runners coupling said mold compound receptacle to each of said die cavity regions; providing a plurality of top die cavity regions each corresponding to a bottom die cavity region is said bottom mold chase; placing a plurality of leadframe and die assemblies on said bottom mold chase such that each of said bottom die cavities receives and supports an integrated circuit die coupled to a lead frame by bond wires; placing a mold compound insert in said mold compound receptacle; placing said top mold cavities over said bottom mold cavities such that the top and bottom mold cavities are brought into contact, the leadframe and die assemblies lying between and within the top and bottom die cavities; compressing said mold compound insert such that said mold compound exits the mold compound insert and begins to move into said runners; and continuing to compress said mold compound insert until said mold compound transfers into said runners and fills each of said top and bottom mold cavities with said mold compound; wherein said mold compound insert comprises mold compound packaged in a sproutless packaging comprising a thermoset resin packaged in a sproutless plastic film that is heat sealed at the edges, the sproutless packaging being burst open where the runners intersect the mold compound receptacle by the pressure caused when the mold compound insert is compressed.
2. The method of claim 1 , wherein said step of providing a mold compound insert further comprises the step of providing a sproutless mold compound insert which is packaged in a plastic film.
3. The method of claim 2 , wherein said step of providing a sproutless mold compound insert packaged in a plastic film further comprises the step of providing a mold compound piece covered in a plastic film that has a heat seal, said heat seal becoming penetrable during the molding process, such that the mold compound exits the plastic package through said heat seal in response to said compressing step.
4. The method of claim 1 wherein said step of providing a mold compound insert comprises providing a thermoset resin packaged in a sproutless package.
5. The method of claim 1 wherein said step of providing a mold compound insert comprises providing a thermoset resin packaged in a sproutless plastic film.
6. The method of claim 1 , wherein said bottom die cavities are coupled to said runners by gate regions, said gate regions restricting the flow of said mold compound into said cavities such that the fill rate of said cavities with said mold compound is a predetermined rate.
7. The method of claim 1 , wherein said step of providing a providing a plurality of runners coupling said mold compound receptacle to each of said die cavity regions comprises providing a plurality of runners that are substantially equal in length such that the distance from the bottom die cavities to said mold receptacles is substantially equidistant.
8. The method of claim 3 , wherein said step of providing mold compound packaged in said plastic film comprises providing an abrasive material, said plastic film isolating said abrasive material from said plunger and said receptacle.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
May 2, 1995
March 11, 2003
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